Safety paper



April 1935. 's s. HIMMELL 1,998,237

SAFETY PAPER Filed Apri l 11, 1933 ATTORNEYS.

Patented Apr. 16, 1935 UNITED STATES PATENT OFFICE 1 Claim.

My invention relates to a new and improved safety paper.

One of the objects of my invention is to provide a coated safety paperhaving a suitable iden- 5 tifying mark directly printed upon the basepaper, said identifying mark being covered by a suitable coating. Thiscoating is of the type upon which an outside printed impression can bemade. Hence a suitable identifying or safety mark can be directlyprinted upon the base paper and the name, trade-mark and the like of themanufacturer can be printed upon the exterior surface of the surfacecoating of the base paper.

While I have referred to a safety paper, it is to be understood that thesafety paper may form either all or a part of a carton or container ofany kind.

According to the present invention the base stock of paper may be lightimpermeable, either due to the thickness or to the structure ,of thepaper. Hence the paper stock can be made of any desired thickness, whichis suitable for making cardboard containers for holding bottles ofmedicine and the like. likewise the paper stock can be made sumcientlythick so that it is suit-= able for the manufacture of tickets and thelike.

According to the present invention the surface coating is made ofmaterial whose light permeability is increased when the same ismoistened so that the protective marking is either absolutely orrelatively invisible, until the surface coating is moistened. Saidprotective marking may be slightly visible as long as the coating isdry, but when the coating is moistened, said protec tive markim standsout prominently.

Another advantage'of the present invention is that the surface coatingdries rapidly so that the protective marking then becomes either ab=solutely invisible or is only slightly visible.

Qther objects of my invention will be set forth 'in the followingdescription and drawing which illustrates a preferred embodimentthereof, it being understood that the above general statement 5 of theobjects of my invention is intended merely to generally explain the sameand not to limit it in any manner.

Fig. i is a front elevation illustrating the improved saiety paper.

Fig. 2 is a sectional view on the line 2-2 of Fig. l.

The base stock of the paper is designated by the reference numeral i.said base stock may be of any type and of any suitable thickness, andits thickness may be as high as 50 points. This paper is absolutelyopaque and it remains opaque even when its surface is moistened.

TIL-S base stock I may be suitably treated so that the protectivemarking 2 can be clearly printed, watermarked, embossed or otherwise ifimpressed thereon. I prefer to print the protective marking upon thebase stock so as to leave the surface of said stock as smooth aspossible, so that the surface coating can be spread smoothly over theprinted surface. The base stock I 10 may be suitably sized so that aclear protective printed marking can be impressed thereon.

I do not wish to limit myself to any particular type of base stock asany suitable type of box board or the like can be utilized.

After the protective marking 2 has been impressed or printed upon thebase stock, the printed surface of the base stock is covered with acoating which may have the following composition although I do not wishto restrict myself to the 20 ingredients or proportions specifiedherein:-

Percent Clay 67 Satin white 18.2 25 Casein 13. 8 Soda ash l The aboveproportions are by weight. From 8 to 3b pounds of said coating areapplied to 500 sheets of the base stock or paper, each said sheet being22 inches by 28 inches.

When-a surface coating 8 of this type is dry, the protective marking 2is either absolutely invisible, or only slightly visible. This dependsupon the thickness of the surface coating 3. Likewise this depends uponthe character of the protective marking because if the protectivemarking is'made with dark or heavy ink, it is more readily visible thanan impression which is made with a light colored ink. That is, if there40 is a sharp color contrast between the ink and the coating, then saidprotective marking is readily visible. If there is a sharp colorcontrast be= tween the ink of the protective marking, and the outercoating 3, the thickness of said outer coat= ing or coatings can beincreased so that the pro= tective marking 2 is only slightly visible orabsolutely invisible. This can be regulated as desired.

When the protective coating 3 is slightly moistened with water, withoutmoistening the base stock itself to any substantial extent, theprotective marking 2 stands out prominently so that it is readilyvisible by reflected light. The effect of the moisture is to render saidprotective coating a relatively transparent so that the light passesthrough the same and the light is reflected back by the surface of thebase stock. In order to increase this effect the surface of the basestock may be white and have suitable reflecting powers. However, anycolor contrast may be provided between the marking 2 and the base stockI, so that the difference in color renders the marl-ring clearlyvisible, when the surface coating is moistened. However, the moisteningof the enamel coating with water does not remove said enamel coating.

The color of the coating 3 is ordinarily white, but this color could beany suitable light color such as pink, light blue or the like.

The protective coating 3 dries rapidly as it requires only slightmoistening for the purpose above described. When the protective coating3 dries, the marking 2 becomes absolutely invisible or slightly visible,this' being regulated in the manner above described.

Hence, when the coating 3 is dry, the protective marking may besufficiently visible so that the mill can determine whether theprotective marking has been properly printed upon the base stock.

The surface coating 3 is ink absorbent so that it can be directlyprinted upon.

It will be noted that the protective coating 3 is made of non-papermaterial. Since the operations of making a protective paper of this typecan only be performed at a large mill, it is practically impossible tocounterfeit said protective paper. The protective coating 3 can beapplied to the base stock preferably while the base stock is unrolledfrom a suitable roll. The identifying mark can be printed at the end ofthe run when the base paper is being manufactured or after said basepaper has been manufactured. For example, the base paper can be runthrough a printing press and it can then be run through a coatingmachine, which applies the coating 3. If desired, a printing machine canbe attached to the coating machine so that the printing on the basestock, and the subsequent coating thereof, is done in direct succession.The surface coating 3 is dried and calendered in the usual manner sothat it can be printed upon. This surface coating or enamel 3 can beapplied to the paper, while the paper is in roll form. I

It will-be noted that this surface enamel or coating contains more thanof opaque pigment material such as clay and satin white. Neverthelessthis coating becomes sufliciently light permeable when it is moistened,"in order to increase the visibility of the protective marking.

In order to define the action of the protective coating 3, when the sameis dry, it may be stated that said protective coating 3 then masks theprotective marking. In using the word masks in the claim, I intend tocover every type of paper in which the visibility of the protectivemarking is increased when the coating is moistened.

I have shown a preferred embodiment of my invention, but it is clearthat numerous changes and omissions can be made without departing fromits spirit.

I claim:

An opaque safety paper comprising a base stock which has a lightreflecting surface, said light reflecting surface having a protectivemarking thereon, said light reflecting surface having a coating thereon,said coating comprising a major proportion of clay and a minorproportion of casein, said surface coating being substantiallylight-impermeable when it is dry, so that the coating then substantiallymasks said protective marking, said surface coating being ink absorbentso that it can be printed upon, said surface coating becominglight-permeable when it is moistened with water so that the protectivemarking can then be viewed by reflected light through said moistenedcoating, said moistened coating being substantially non-removable by theaction of water, said base stock being opaque.

SAMUEL S. HIMMELL.

